Wednesday, January 6, 2016

The current strong El Niño brewing in the Pacific Ocean shows no
signs of waning, as seen in the latest satellite image from the
U.S./European Ocean Surface Topography Mission (OSTM)/Jason-2 mission.

El Niño 2015 has already created weather chaos around the world.

Over
the next few months, forecasters expect the United States to feel its
impacts as well.

The latest Jason-2 image bears a striking resemblance to one from
December 1997, by Jason-2's predecessor, the NASA/Centre National
d'Etudes Spatiales (CNES) Topex/Poseidon mission, during the last large
El Niño event.

The images show nearly identical, unusually high sea surface heights
along the equator in the central and eastern Pacific: the signature of a
big and powerful El Niño.

Higher-than-normal sea surface heights are an
indication that a thick layer of warm water is present.

People the world over are feeling, or soon will feel, the effects of the
strongest El Niño event since 1997-98, currently unfolding in the
eastern equatorial Pacific Ocean.

New satellite observations are
beginning to show scientists its impact on the distribution of rain,
tropospheric ozone and wildfires around the globe.

El Niños are triggered when the steady, westward-blowing trade winds
in the Pacific weaken or even reverse direction, triggering a dramatic
warming of the upper ocean in the central and eastern tropical Pacific.

Clouds and storms follow the warm water, pumping heat and moisture high
into the overlying atmosphere.

These changes alter jet stream paths and
affect storm tracks all over the world.

This year's El Niño has caused the warm water layer that is normally
piled up around Australia and Indonesia to thin dramatically, while in
the eastern tropical Pacific, the normally cool surface waters are
blanketed with a thick layer of warm water.

This massive redistribution
of heat causes ocean temperatures to rise from the central Pacific to
the Americas.

It has sapped Southeast Asia's rain in the process,
reducing rainfall over Indonesia and contributing to the growth of
massive wildfires that have blanketed the region in choking smoke.

El Niño is also implicated in Indian heat waves caused by delayed
monsoon rains, as well as Pacific island sea level drops, widespread
coral bleaching that is damaging coral reefs, droughts in South Africa,
flooding in South America and a record-breaking hurricane season in the
eastern tropical Pacific.

Around the world, production of rice, wheat,
coffee and other crops has been hit hard by droughts and floods, leading
to higher prices.

While El Niño may provide some drought relief locally, in other parts of the world, it wreaks havoc.

In the United States, many of El Niño's biggest impacts are expected
in early 2016.

Forecasters at the National Oceanic and Atmospheric
Administration favor an El Niño-induced shift in weather patterns to
begin in the near future, ushering in several months of relatively cool
and wet conditions across the southern United States, and relatively
warm and dry conditions over the northern United States.

While scientists still do not know precisely how the current El Niño
will affect the United States, the last large El Niño in 1997-98 was a
wild ride for most of the nation.

The "Great Ice Storm" of January 1998
crippled northern New England and southeastern Canada, but overall, the
northern tier of the United States experienced long periods of mild
weather and meager snowfall.

Meanwhile, across the southern United
States, a steady convoy of storms slammed most of California, moved east
into the Southwest, drenched Texas and -- pumped up by the warm waters
of the Gulf of Mexico -- wreaked havoc along the Gulf Coast,
particularly in Florida.

"In 2014, the current El Niño teased us -- wavering off and on," said
Josh Willis, project scientist for the Jason missions at JPL.

"But in
early 2015, atmospheric conditions changed, and El Niño steadily
expanded in the central and eastern Pacific. Although the sea surface
height signal in 1997 was more intense and peaked in November of that
year, in 2015, the area of high sea levels is larger. This could mean we
have not yet seen the peak of this El Niño."

During normal, non-El Niño conditions, the amount of warm water in
the western equatorial Pacific is so large that sea levels are about 20
inches (50 centimeters) higher in the western Pacific than in the
eastern Pacific.

"You can see it in the latest Jason-2 image of the
Pacific," said Willis.

"The 8-inch [20-centimeter] drop in the west,
coupled with the 10-inch [25-centimeter] rise in the east, has
completely wiped out the tilt in sea level we usually have along the
equator."

The new Jason-2 image shows that the amount of extra-warm surface
water from the current El Niño (depicted in red and white shades) has
continuously increased, especially in the eastern Pacific within 10
degrees latitude north and south of the equator.

In the western Pacific,
the area of low sea level (blue and purple) has decreased somewhat from
late October.

The white and red areas indicate unusual patterns of heat
storage.

In the white areas, the sea surface is between 6 and 10 inches
(15 to 25 centimeters) above normal, while in the red areas, it is
about 4 inches (10 centimeters) above normal.

The green areas indicate
normal conditions.

The height of the ocean water relates, in part, to
its temperature, and is an indicator of the amount of heat stored in the
ocean below.

Within this area, surface temperatures are greater than 86 degrees
Fahrenheit (30 degrees Celsius) in the central equatorial Pacific and
near 70 degrees Fahrenheit (21 degrees Celsius) off the coast of the
Americas.

This El Niño signal encompasses a surface area of 6 million
square miles (16 million square kilometers) -- more than twice as big as
the continental United States.

While no one can predict the exact timing or intensity of U.S. El
Niño impacts, for drought-stricken California and the U.S. West, it's
expected to bring some relief.

"The water story for much of the American West over most of the past
decade has been dominated by punishing drought," said JPL climatologist
Bill Patzert.

"Reservoir levels have fallen to record or near-record
lows, while groundwater tables have dropped dangerously in many areas.
Now we're preparing to see the flip side of nature's water cycle -- the
arrival of steady, heavy rains and snowfall."

In 1982-83 and 1997-98, large El Niños delivered about twice the
average amount of rainfall to Southern California, along with mudslides,
floods, high winds, lightning strikes and high surf.

But Patzert
cautioned that El Niño events are not drought busters.

"Over the long
haul, big El Niños are infrequent and supply only seven percent of
California's water," he said.

"Looking ahead to summer, we might not be celebrating the demise of
this El Niño," cautioned Patzert.

"It could be followed by a La Niña,
which could bring roughly opposite effects to the world's weather."

La Niñas are essentially the opposite of El Niño conditions.

During a
La Niña episode, trade winds are stronger than normal, and the cold
water that normally exists along the coast of South America extends to
the central equatorial Pacific.

La Niña episodes change global weather
patterns and are associated with less moisture in the air over cooler
ocean waters.

This results in less rain along the coasts of North and
South America and along the central and eastern equatorial Pacific, and
more rain in the far Western Pacific.

El Niño events are part of the long-term, evolving state of global
climate, for which measurements of sea surface height are a key
indicator.